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必威娱乐平台官网碳链簇合物的结构和光谱性质的理论研究-万贯国际_万贯娱乐_糖果派对漏洞破解_【官网入口】

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  【必威国际唯一指定官网】【必威国际唯一指定官网】碳链簇合物的布局和光谱性质的理论研究化学取阐发化学工程硕士论文,结业论文,论文格局,论文参考,结业论文格局,格局参考

  中文摘要含碳普遍存正在于星际介质中,它们正在恒星,原始,小的构成以 及研究生命的发源中饰演着主要的脚色。这些含碳的大多是碳簇,包 括纯碳簇(ca,Q等)和代替碳簇(QS,c8II,HCIlN等)。正在烃燃烧的火焰中和其 它的能构成烟灰的系统中也有碳簇的存正在.碳簇仍是很多化学反映的两头体, 某些碳簇还具有出格的电学性质。因为它们和物理学,化学,燃烧过 程,电子学以及材料科学都相关,对碳簇的研究成为人们关心的核心之一。 链状碳簇可分为两种,雷同累积烯布局的和雷同聚炔布局的。因为它们具 有极高的反映活性,正在尝试室中难以合成。计较化学不需要正在尝试室中合成或 者提取出物质,就能够预测的各类性质,并且预测值和尝试值凡是合适得 很好。做为计较化学的一个主要构成部门,量子化学能够做高精度的计较,对 小系统的各类性质做出理论预测。激发态的研究对材料科学、发光科学以 及星际介质化学都很主要,因而,本论文就以量子化学为东西,研究碳链簇合 物的电子光谱性质,为尝试以及太空不雅测供给理论根据。所选系统很典型,很 普遍,有质子化阳离子系统c.W,有等电子系统CNS、C#Cl+,有阴离子价等电 子系统C玉O-、cks-、C锄Sc-,也有碳链两头同时被代替的中性系统PCzP. 量化计较的方式如下: 系统基态的均衡几何构型是用密度泛函理论优化获得的,同时计较谐振动 频次和红外强度,以确定所优化构型的不变性。激发态的几何构型是用完全活 化空间自洽场的方式优化获得的.正在所优化的几何构型下,用完全活化空间二 阶微扰理论(目前精度最高的计较方式之—)计较了系统的垂曲激发能,垂曲 发射能和垂曲解离能。响应的阵子强度是用态取态之间的跃迁偶极矩来计较的。 对系统c届、C心l+,单态一叁态跃迁可能性用自旋一轨道耦合组态彼此感化方 法(SOC-CI)来估算。 计较表白,理论预测值和可获得的尝试值合适得很好。计较不只对尝试中 的谱峰给出了指认归属,并且还预测了一系列新的谱峰以及一些尝试室尚未合成的系统的电子光谱。代替碳链簇合物的很多性质都具有奇偶效应,即含奇数 个碳原子的系统取含偶数个的性质分歧,细致如下: 1.~般来说,对所选择的这些碳链系统,大大都曲线构型是不变构型。对 c小r、CNS和c棚+系统,当为奇数时,基态是单沉态X1r,具有…矿,矿或 者…。甜矿的电子组态;当为偶数时,基态是三沉态X3r,具有…—矿筇2矿的 电子组态。对价等电子系统C2。0-、c-2,ls-和C2,ISe?来说,基态是双沉态X2II,具 有…删石‘铲的电子组态。对两头同时被磷原子代替的磷炔P%P来说, 基态是单沉态X1譬,认为奇数时,电子组态为…硝础(桫;刀为偶数时, 电子组态为…O(趸O秽。 2.跟着碳链系统的增加,cm+、c2一s、c2。o-、c2|lsi和C锄Se-中碳原子取杂 原子之间的键长C--X()(=H,o,S,Se)逐步减小,C知Cl+、C山.ICI+和c2,1.1S中碳 原子取杂原子之间的键长逐步添加,PC2,中碳原子取杂原子之间的键长根基保 持不变。CNS中c.c键长具有雷同累积烯的布局特征,趋于平均化,而正在离子 系统c棚+,c—cl+、c2。旷、c知s一和c抽sf中,C_键长具有单叁键交替的布局 特征。可能是由于聚炔布局能分离离子电荷,使离子簇合物愈加不变。 3.计较获得的振动频次成果表白,所有系统的最小弯曲振动频次都很小, 且跟着系统的增加,频次越来越小,响应的强度也逐步减小,以至几乎消逝, 这些是柔性。 4.跟着碳原子数的添加,所有系统的偶极矩逐步添加,而动弹逐步减 小。一般地,偶极矩从小到大的次序为CCl+<C艄稿<c0kc《辅f。 5.CCl+、C席r和CN¥中杂原子带正电荷,阴离子系统e矿、C格-和C^^Se- 中杂原子带负电荷。跟着系统的增加,杂原子上所带电荷逐步减小。取端基原 子相连的碳原子带负电,链两头的碳原子带正电。 6.统一系统中,含有奇数(或偶数)碳原子的系统的垂曲激发能具有类似 的能级次序;对分歧系统,州+、CNS和cCr,以及cz。o-,Q。s-和C知Se- 的垂曲激发能也具有类似的能级次序。一般地,跟着碳链系统的增加,到不异 激发态的垂曲激发能逐步减小。垂曲发射能也逐步减小。因为激发态的振动弛豫,发射光谱相对于接收光谱呈现了红移。 7.SOC-CI计较表白,含偶数个碳原子的c2届和CzCl+中禁阻的21寸—x3F 跃迁可能会发生,而含奇数个碳原子的ChIS和C绋lCl+中单叁态跃迁的阵子强 度都很小,叁沉激发态很难通过间接单一叁态跃迁达到。 8.比力计较到的PQ,的垂曲跃迁能和电离能取文献报道的NC2。N、 HQ—tN、NC2j'和Hc船lP的垂曲跃迁能和电离能可发觉,PC2J'的垂曲跃迁能 和电离能最低,NC2。N的垂曲跃迁能和电离能最高。前者可能是因为电子离域 效应惹起的,后者可能是由电负性惹起的。并且还获得了垂曲跃迁能和电离能 取系统大小之问的解析表达式,依此能够预测较大系统的相关性质。 环节词;碳链簇合物;星际;电子光谱 nl AbstractCarbonaceous molecules撇widelypresent ininterstellar andcircumstellar mediums.Theyplay all important roleintheformation ofstars,protoplanetarydisks planctesimalsand inthe study ofthe origin oflifo.Mostofthesemoleculm撒‘ carbon clustersincludingpure carbon clusters(C2,Q,咖.)and substitutedcarbon dusters(C以C2S,HCIINetc.).Carbon clustersarealsofoundtobe present hydrocarbonflames andother soot-forming systems.They arc thought intermediatesformany chemicalreactions.Some kinds黜reported tohave xtraordimry clcctromc plq'eme文They肿correlative astrophysicscosmicchemimycombustionmolecular electronicsandmaterialscience。Sostudies011 themhaveattractedmuchattention. C-挑11chRillclusterscanbedividedintotwo type9 oumulencand polyyne. Howevercarbon clustershave highreactivitywhich difEenlttoproduoin laboratory.Computationalchemistry doesn'tneedto synthesize or哟‘tractmatterin laboratorybut can predict various properties ofmolecules.Andtheresults usually showreliable agreement withthe experiment.Quantlmlchemistryas computationalchemistry啪dohighaccuracycalculationsonsmall systems.A thoroughunderstanding ofthe e.xcited-state propertiesis importantformaterial SCienCeluminescenceandchemistry oftheinterstellarmedium.Asa resultthe aim ofthisdissertationisto study thestructuresandelectronic spectra ofcarbonchain clusters byquantum chemical caleulatiom,and supply theoretical basis experimentsandastronomicalobservations.Theselectedsystems arc typicaland extensiveincluding carbonchaincationsch礴,isoelcctroniccarbon幽出晦c添, C柑’,valence isoelectronic carbon chainanions Oz^O-C知S-C知Se-and disubstitutedneutralcarbonchainsPC2^P.1nhccomputational methodsare雒follows: 111e geometries ofthe ground statesate optimized丽thdensity functional theory. Thevibrational frequencies andIRintensitiesaroalsocalculatedafterthe geometry optimization砒the¥alne levd oftheory.Thegeometries ofthesdectedexcitedstates CompleteActive Space SelfConsistent Ficld(CASSCF)method. Afterthe geometries arc locatedthe vertical excitation髓ergi翻,vertical emission energies andV响caldetachment energiesacomputed CompleteActive Space SecondorderPerturbation Theory(CASPT2),which isknownasoneofthemost accuratemethodstocalculateexcitedstates.The con-csponding transition dipole momentsarecalculatedtoobtsmtheoscillator strengths.ForCs cCl+’thesingle-triple transition probabilit)r isestimated bySpin Orbit CouplingConfiguration Interaction(soc-coapproach. It revealsthat theoreticallypredictedvalu酷show goodagreement withthe availabteobservedvaIUl鹪.Thecalculationsnot onlygive assignmentofthe absorptionpeaks previousexperimentsbutalso predict othernew peaks andthe electronic spectra ofthe systems thathaven'tb啪observedin lab.Furthermore manyproperties ofsuchsubstitutedcarbonchaindustersexhibit parity cfjfect.See belowindetail: 1.In general,forthecarbonchainsconsidered herealmost all thelinear structuresarestable.Forc对,CNSandCNCl+,whenNis oddthe linear ground stateisa singlet whenNiseventhegroundstale tripletstateX譬withtheelectronic configurationas…未孑亡隶?Forvalenceisoeleetrunie speciesQh镬。C砷S-and c2Ilse-,theground stateisx2nwiththeelectronic configuration勰…矿矿矿矿矿.111c PC2^Ppolyynes havethe singletground state X1譬with anelectronic configuration 2.AsthechainsizelengthensC-Xg=H,0,S,sO bond l碘inC^籽, %S,C2,I矿,%s.andC2^Se-decreaseslightly;C-X=S,CI)bondlengths C知CI+,Ch.iCl+andC缸ISincrease slightly;C-X=P)bondlengths inPC2nPkeep almostthesame.InCS。theC—Cbondshaveacumulenic structureand tendtobe equalization.While inions C知旷,C#CI+,c么o-C抽S’andC2-Se-,thebondlgIh3 ofC-Cbondsneartheheteroatomshavea single-triple alternate bonding character. This acetylenicbondingmaydisperse suchcarbonclustersthrough conjugation interactionanditwillstabilizetheionicclusters. VI 3.11艟calculatedIRf掀luencies showthattheminimuln bendingfrequencies arc very small.Withtheohaill lengthemtheydecreaseand cmrespondingintensities also decreasenearly vanished.Suchmoleculesare floppy. 4.Withtheincrease of弗,thedipolemoments increase9 whiletherotational constantsdecrease.In generalwith thesamenumberofcarbon atomsthedipole momentsincreaseintheorder 5.oeneratly'theheteroatoms in(:正Il十,ck女r bearpositivecharges whilein cr。CtvS-andC~Se-they have negativecharges.As increasesthecharges ontheheteroatomsdecrease.Foranthechainsconsidered herethe second atomsonbothendsofallthesecarbonchainshavenegativecharg酷,while thecarbon atomsinthemiddleofthechainshavepositivecharges. 6.耵伦predicted verticalexcitation energies ofCj矿C精andc—cl+havea similar pa性em withodd-Nandeven-N respectivelX andSOdoc2no-.c2^s-and C2HSe-。In general asthecarbonchaiB lengthens,the verticalexcitation energies theganleexitedstatesdecreasegraduallyand theverticalemissionenergies exhibit similarbehavior..11艟verticalemissionsexhibitlessredshiftduetorelaxationofthe excitedstatewith mq成-t totheir correspondingabsoqtionspeara. 7.SOC.CIcalculationsshowthat only theforbidden21矿+o(jZ-excitationfbr c2蒂褴dC锄CI*maytake#ace.But C2=ISmid C2月.1C1+,theoscillator殉舶啦s singlet-triplettransitionsarc generallyvery smallandtheseexcited triplet statesin bothisoelectronicseriesarelossaccessible directsingtet-iriplet transitions. 8.皿everticaltransition ener酾and ionization enegiesofPC锄P comparedwiththoseoflinear NCz。N,HQ计nN,NC2nPandHC讲nP,and discoveredthatzhandZEofPQ,a稽thelowestwhilethoseofNC2,lNarethehighest.The former may becaused thedifferentelectronicdelocalizationeffectandthelatter may becaused byd蜘llegafivies.Anexplicit non-linear analy6cal expressionbetween研(orIE)and雄has beenobtainedfromwhichWO c柚predict西 (Z回withlarger筇. Keywords:carbonchaindusters;interstellarmolecules;electronicspecaa 关于学位论文完成和内容立异的声明本人向河南大学提出硕士学住中请。本人声明:所呈交的学位论文是 本人正在导师衲指点下完成的,对所研宄的课趣有新的看法。搪我所知,除 文中出格加以申明、标洼和称谢的处所外。论文中不包罗其他人曾经颁发或撰 写过的研宄,也不包罗其他报酬薮得任何教育、科研拟构的擘住或证书而 利用过酌材料。取我一同工做的同市对本研究所徽的任何贡献均已正在论文中做 了明白酌申明并暗示了谢惑。 学位申请人(学化论文做者)签名: 20D7年垆月w日关丁二学位论文著做杈使刖授权书 本人经河南大学审核核准授了硕上学位。做为学位谚文酌做者,本人完全 领会并同意河崩大学相关保留、使川。学位论文的要求,即河南大学有权向国度 藏书楼、科研信,g机摘、数据收集机掏和本校藏书楼等:供给学住论文(纸质文 本和电子文本)沮供榆索、饩I蒯。本人授权河南大学出于、展览学校 学术成长和进行学术交换等月的,叫以采收影E、缩印、扫描和拷贝等复制手 段保留、汇编学位论文(氟质文本和电子文本)。 (涉及保密内容的学位论文正在解密后合用本授权书) 学位获得者(学住论文做者)签名:星垒鸱 20D7年驴月w日 学位论文指点敏师荽名: Introduction1.1 CarbonChams 1.1.1 11地E盖lsteneeofCarbonChains The space betweenthestarsisnotvaaluIn,butfilledwithinterstellar ma£t1% mainlycomposed ofdustandgaswhichgather largeinterstellarclouds.These interstellarmoleculeswcrofoundtoscfveas extremely useful dia粤的sdc toolsofstar formationandthe dynamics oftheinterstellar 0S)medium general【l】.What种theszintersteHarmolecules?Itis reported m哪than130interstellarmoleculeshavebeen identified(Table 1.1.11.Mostofthemaneutral moleculesorradicals,and80mearecations.In2006,thenegative molecularion C6壬r wasdetectedin theradiobandinthelaboratoryandwasfirstidentifiedinthe molecular envelope of取C+10216andinthedensemolecularcloud 1MDl【2】. Fromthenonneuralmoleculescationsandanionshavebeenalldetectedin space. Among theseinterstellarmolecules,B101.e than100molevalesare C-bcering molecules.andone component ofinterstellardustiscarbonaceous.Carbonisa major player intheevolutionaryschemeoftheuniversebecauseofitsabundanceandits abilitytoform complexspcci翻(singlebonddoublebond,triplebond).It isalsoa keyelementintheevolutionofprebiotic molecules.n比cosmicevolutionofCfiom theinterstellarmedium(ISM)intoprotoplanetarydisksand planetesimals,andfinally ontohabitablebodiesisin血'insictothe study ofthe originoflife【3】. Among C-bearingmoleculesdetectedin spar冶c—arbon-chain mohxmleshave emerged asthemainarchitecturalthemeofinterstellarandcircumstellar space.Some purecarbonclusterssuch Q,C3,c4andCs,somearesubstitutedcarbonchainmolecules(Cm,C捌,C.O,C.S,GSiHC.N).Afterthey weredetected 粕缸0llhysicalsoursthe carbonmoleculescontinuetobe intenselystudiedin connection硒mthechemistryof comets【41,carbonstars【56】and interstellar molcenlar clouds【7_lo】.Long carbonchainshavebeen proposed possiblecarriersofthediffuseinterstellar bands(Dins)【ll,12]. H2c3幽H cII,c刘CH3Cffl 013C# I-H2C4 C2H4 CH3C'N CHiC CH30H CH3SH HC剑H+ HC!CHO NH2CH0 CsN HCN (cH3hco NHCI-12cOOH CH3CH2clHO HCIINCH,OC2Hs 1.1.2 ABriefIntroduction toCarbonChains In factCal'bon clustersarenot only existentin spacethey arcalsoknowntobe present hydrocarbonflamesandother soot-formingsystems[13—151,mad studyofthese species isnecessary acquiringathoroughunderstanding ofthese complex 逐个叩峨逐个逐个蜊逐个逐个 叫叫吼蝴一吼酬逐个逐个一鹏帆一 chemicaletlvironments.Carbondusters黜alsothought tobeintermediat璐intlae gas-phasochemistrytakingplaeo inchemical VttpOl"dcpositiollsystems productionofthindiamondandsiliconcarbide films【16,17].SOml。kinds勰thought tohave extraordil哪electricalproperties【18].Clearlya detailed knowledge ofthe physical andclaemieall lX'1)pct"tiCS ofca击眦dustersis important undemanding矗largevarietyofchemical systems.In additiontosuch practicaleomideratiomcarbon dusters啪fascinatingexample8 oftherielmessand varicty ofcarbon chemistry itself.Duetothea101t'mOUSbonaingflexibility ofcarbonitstmiqucability toform stable singledouble01"triplebonds,Clltbon dusters appear inawide range slrueturalformsthatasynthesizedspontaneously inhotclll'bon plasmas.As aresult studicsoncarbondustershaveattractedmuch allention【t9-21]. Purecarbondustersc粗be produced inthe laboratoryby laserablationofa graphitetargetandthey锄known toexistinarieda variety ofstructuressuchas linear chains,rings andfullerene cages(Figs.1.1.1 1.1.2,fromRef.【2l】).Thelinearchaillisthemoststableformfordustersof roughlyup to10carbon atomslargermolecules眦supposed occur勰ringsOlrdosedthree-dimensional cages【2l】。Carbon ch抽玛canbedividedintotwo typ璐,蛆e istheeumulenewith doubledouble boncling(:C--C=C=C=C.)'the otheris acetylene single-tripleconjugatedbonding(-仁-C--C=--C。1.Pure carbollchaioswithe嗽numberatomsn bothhaveeumulcnieandaeetyleniebondingbut theoddnumberdusterscan only haveeummulenie bonding.Asearly勰1959 Pitzerand Clementi【311 foundthatthe moststableearbon础n bonding forsmalllineardustersisaeumulenic bonding rathel"than anaeetyleniebondingbymolecularorbitaltheory. Thefirst rotationaUy resolvedinfrared spectrumofa pure Clllaoondusterwasthe steemlm w强defiedintheenvelope ofthecarbonstar IRC+10216【5】.In 1989linearC5Wall detectedin IRC+10216【5】and inthe laboratory[33.34],In al,publishedrotationallyresolved infrared gas-phasespectra oftheevennumbered C4【35】andC6【36】elllsters andthe odd numbered劬[37,381 c9[39,40lusingalaserablationCa/bOlldusterSOUI'C宅 incombination谢lhasensitiveinfraredtunablediode laser驰31rometer. FIg.1.1.1Equ狮rlumgeometries ofthe10w-eneqm'ucturalisomersofsmallcarbon cluster&Bond iengths(A'andbond angles(degrees)were calcuiatedforeachcluster" folows:C如CCSD口)/cc-pVQZ【221;linear cyclicC4,CCSD(T)/PVTZ1231;C9 CCSD(Y)/275cGTo毫l矧;linear%RCCSD(T)/204cGTOs1251;cyclicC6CSD盯),rZ2P 1261;C7,MCCSD(T)/238cGTOs1271;linear CsRCCSDtT)/cc-pVTZ1201;cyclic Cb CCSDfr)/cc-pVDZ;andc’,CCSDfr呻VDZ1291. FmkFig.1.12Structuralisomers ofC犷11,301 Intheselinearl'bonchainstheatomicorbitals躺sphybridized.Carbon chainssuch manyas11 carbon atoms hadbeenobservedin theinterstellar medium【4l—43】’姐d evidencefortheexistenceofeven largersped髓 ofthiskindwasobtainedfrom laboratorymeasurements【44—46】.Lagow cta1.have also synthesized bulk quantities ofsuchcarbon chaii丛containing manyas28 c81Joonatoms bystabilizing theterminalcarbonswith buUqorganicend-capping groups【47】.According them"observations,theysuggestthatthese long chainsof sp-hybridized carbonatoms may constitutea"fourthstable allotropeofcarbon"after diamondgraphi_lemd fallcrone. Purecarbonclusters are:highlyreactivetransientspecies.In theinterstellax mediumthere.activity ofsmallcal惋nclustersisforfdted byquasicollisionleas conditionsand carbontakesthe higlllystablealbeithighly reactiveformoflineaf chai鹤【48-50】.But inthe laboratorydue totheir lli曲reactivitymc)r ago extremely difficultto produce study.Whatc瞄wedoto studythem?Yes.exceptstud徊g them exp盯imcntallyWe 锄also study them theoretically.Computationalchemistry doesn’tneedto synthesize Orextractmatterin laboratorybut call predict various properfi嚣ofmok圮mlessuch [ISstable s协肭l嘲,dipolemomentsionizationpotential,electronaffinityinfrared spectraNMRspectraultravioletspectrareactionpathand SOOn.Andtheresults usually showreliable agreement withthe experiment.For themoleculesthatarc difficultto synthesize lab.computationalchemistryalmostbecom嚣the onlyway computationalchemistrycando hi曲 accuracy calculationsonsmallsystems.Thismethodhas already beenusedto pr钱iiot propertiesoflbdusters.Hoteroatomterminatedcarbondusterssuch勰晒 钒B,F,siCI,他V,CrFeNi,W,ZrCsRb,AI,N,P,趣Bi,S,Sc'ete.) havebeen reported tobe producedby laser ablating propersamplesandbestudied bytime-of-flightma豁spectrometry[51,52】.Based Oilabinitiocalculationsandthe observed experimentthe researchers predictthat昭should havelinearstructtlres withheteroatomXlocatedOnone%doftheCalbOnchain.A symstcmatic investigation hasbeencarriedout011 second-row—atom-doped linearcarbonclusters CmGX—『Cnr(,Fl—lo,X=NaMgAI,siP,S,C1)【53】usingdensityfunctional theory(DFT-B3LYP)method conjunctionwith6-311+G*basis setincluding low-lyingstatestotalenefgi鹞,geometriesincrementalbindingenel'gles)ionizationpotentials,andelectronaffinities.Itshowsthat theincremental bindingenergy ionization potential andelectron amnity exhibitdifferent parity alternafioneffectsin theirstabilities. Purerbonclusters咖alsobesubstituted011both ends,such HC.N【4l—46】,H;PAu(C=-C)JIIsmPHs【54]andSC.S【55].Eithersingle substitutionordisubstitution c跚modify propertiesofcRrbollchains.Suchsubstitutedcafoonclustersalso show parity alternationeffects.For instancetheground 8ratesofH晚挪have triple-singlealternative acetylenic structure f561,while theodd-mnnberedpolyynesbeyondHCvH,there isall acetylenic structureinthe vicinityoftheH atoms andacumulenicstructure middleCCbonds【57】.It reveals anonlinear dependenceofthe excitation energy 011 thenumberofcarbonatomsfor

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